Two-stroke-cycle internal-combustion engine



Oct. 23, 1923.

2 Sheets-Sheet 1 Filed Aug. 4, 1927 LIfll fizuewr: 07. az. wanna ry,

A u W m I kE i U. 4

Patented Oct. 23, 1928.

UNITED STATES ARTHUR OSKAR LEONARD WENNERBY, OF GOTTENBURG, SVIEDEN.

TWO-STROKE-CYCLE INTERNAL-COMBUSTION ENGINE.

Application filed August 4, 1927, Serial No. 210,882, and. in Sweden July 20, 1926.

This invention relates to a two stroke cycle internal combustion engine which has proved to embody many distinguished advantages. Thus it may be regulated within wide limits 5 of revolutions, for instance from 800 to 100 revolutions per minute, and it works excellently well with all sorts of fuels, such benzine, paraffin, spirit, crude oil or the like hydrocarbon oils. The engine is especially adapted to be started by means of a lighter fuel, such as benzine, and thereafter to be driven by a heavier fuel such crude oil, and the change over from the lighter fuel to the heavier fuel may be performed only a few minutes after the engine has been started, Further the engine distinguishes itself by an almost noiseless running due to a specially good and well adjusted lubrication which acts entirely automatically.

Further the engine distinguishes itself by a high degree of efficiency and easy management and a durable and simple construction in whicl'rthe machining of practically all machined surfaces may be carried out by of production.

There has already been proposed a two stroke cycle engine in which the cylinder enclosing the working chamber is arranged to be reciprocated upon a fixed cylinder head and to constitute simultaneously a piston in a surrounding fixed compressor cylinder for dra 'ing in and preliminary compressing the air and the fuel and for introducing the charge into the working chamber of the n'iovable cylinder. The engine according to this previous proposal has, however, many very considerable disadvantages, so that the same cannot assert itself under practical working conditions. Among other things the admission ports leading to the working cylinder at the end of its explosion stroke are arranged at both cylinders at the ends opposite to the fixed cylinder head, whereby sufficient space for mounting the necessary number of packing rings between both cylinders to make them tight against the explosion pressure is not at disposal, and vhereby further the charge entering the working chamber flows in the direction towards the fixed cylinder head which in itself may be easily cooled, instead of flowing towards the bottom in the working cylinder, w rich is mostly subjected to heat and which for its cooling is depending almost exclusively upon the cooling action of the charge turning on a lathe, which reduces the costs flowing in. In the previously proposed engine the suction ports for air and fuelat the compression cylinder are further so arranged in the latter, that they are closed by the working cylinder already at the beginning of its explosion stroke or its movement away from the fixed cylinder head and further the arrangement on the whole is such that any automatically effected lubrication of the gliding surfaces between both cylinders other than by lubrication means added to the fuel is excluded.

Also the engine according to the invention has a working cylinder movable upon a fixed cylinder head, which simultaneously constitutes piston means in a surrounding compressor cylinder, in which however, considerable differences are present in comparison with the said previously proposed engine with respect to the arrangement and mode of operation, as will come forth in the following.

The invention is illustrated in a preferred form of embodiment in the drawing in which Figs. 1 and 2 show two vertical sections through the engine, at right angles in relation to each other.

Referring to the drawing 1 designates the crank shaft of the engine, which. is journalled in the crank housing, in the upper part of which are arranged guide members 2 for a cross head 3 with which the con necting rod 4 is connected. The cross head 8 is connected by means of a piston rod 5 to a working cylinder 7 in the form of a piston reciprocably mounted within a fixed cylinder 6 which, as shown, may be cast preferably in one piece with the upper part of the crank housing. The working cylinder 7 is provided at the end opposite to the crank shaft with a bottom 7 in which the piston rod 5 is securely fixed. At its opposite open end the working cylinder 7 fits displaceably upon a cylinder head 8 which is securely attached to the upper end of the fixed cylinder 6 and projects to some length into the latter, a sufficient number of piston rings 9 for tightening against the explosion pressure being arranged between the head 8 and the movable cylinder 7, and further a piston ring 10 which is enough for tightening against the preliminary con pression pressure, is mounted at the lower end of the working cylinder 7 between the latter and the surrounding xed compressor cylinder 6. This latter is provided at its lower end with a detachable bottom preferably in the form of a disc 11 having a central opening through which the cylindrical piston rod 5 passes, and in which annular packing members'l2 are arranged to surround the piston rod.

The cylinder 7 does not fully extend to the bottom 11 in the cylinder 6, and in its lowermost position, as shown in the drawing, there is a free space 13 between the cylinder bottoms 7 and 11, and this space is in permanent communication with a pair of ports 14 and 15 preferably arranged diametricallly opposite each other in the cylinder wall 6. On a level with the lower edge of the fixed cylinder head 8 there is further provided in the cylinder 6 an inlet port 16 and an exhaust port 17, both of which are also suitably arranged diametrically opposite to each other on the same side as the ports 15 and 14 respectively. lVith the ports 16 and 17 other ports 16 and 17 in the reciprocating cylinder 7 coact, in the lowermost position of which cylinder the latter ports are in register with the former, as shown in the drawing. The exhaust port 17 is in communication with a jacket 18 provided with a boss or the like 18 for connection to an exhaust pipe. Substantially centrally in this jacket a chamber 19 is placed and connected to the port 14, A double carburettor 20 is by means of a non-return valve 21 connected to the chamber 19, whereby the said valve is suitably surrounded by a copper tube 22 extending into the chamber and having an open upper end. The port 15 is by a channel 23, suitably carried out in the form of a separate member 24 atiixed to the side of the cylinder 6, in permanently open connection with the port 16.

As well the cylinder head 8 as the cylinder G-itself are arranged to be water cooled The cooling water chamber 25 in the cylinder head 8 stands in direct communication with the cooling jacket of the cylinder 6, said jacket being substantially on a level with the bottom 7 in the cylinder 7 when the latter is in the lowermost position, divided in one upper compartment substan tially surrounding the cylinder 7 at the whole length of its stroke and another lower compartment 28 extending below the cylinder bottom 11. The member 24 forming the channel 23 is also provided with a cooling water jacket 29 which serves to interconnect the jacket compartments 27 and 28 of the cylinder 6. The greater part of the cooling water passes through the cylinder head 8 and the upper jacket compartment 27 of the cylinder 6 only, but a smaller part passes also through the acket or channel 29 in the member 24 to the lower jacket compartment 28 of the cylinder 6 and from there by a suitable connection pipe (not shown) to a jacket surrounding the carburettor 20 for obtaining a preliminary pre-heating of the fuel and eventually also of the combustion air. 7

The crank shaft housing is adapted to take up a certain quantity of lubricating oil and on the pitman bearing is affixed a splash spoon 30 diving into the lubricant and splashing the same about within the crank shaft housing so that all parts contained therein are amply lubricated and a small quantity of lubricant oil for each revolution of the crank shaft 1 introduced into the chamber 13 along the piston rod 5 through the opening for the same in the compar tively thin cylinder bottom 11.

The manner of operation is as follows At the start thedouble carburettor 20 is adjusted for the lighter fuel, for instance gasolene. and when the engine is started the cylinder 7 moves upwards whereby the combustion air and the fuel through the carburettor and non-return valve 21 is sucked into the chamber 19, the chamber 13, which is in permanent connection with the former, and the channel 23. lVhe'n thereafter the cylinder 7 moves downwards the combustible mixture thus sucked in is compressed and,

when the cylinder reaches its lowermost pos tion, it is injected into the cylinder 7 throu h the corresponding inlet ports 1.6 and 16 in a. direction towards the cylinder bottom 7 The charge thus introduced into the cylinder 7 is further compressed during the up ward stroke of the cylinder and is ignited by the spark plug 31, when the cylinder ap-, proaches its uppermost position. By the explosion pressure the cylinder 7 is then driven downwards, and the only place, where a tightening against the high explosion pressure is needed, is at the piston rings 9 for which ample space is available without intrusion on or diminishing o f'the suitability of the construction in other respects. When the piston 7, after completing the power stroke, changes direction of travel and again approaches its uppermost position the outlet ports 17, 17 are first brought into register for exhaustion of the burnt gases and immediately thereafter the inlet ports 16, 16 are opened for injection of the fresh fuel mixture which latter, when entering the cylinder, bailles against the cylinder bottom 7, cools the same and expels the rest of the burnt gases before all of the ports are closed again and another compression stroke commences. As soon as the engine, after the start, begins to get hot the double carburettor 20 is adjusted again and now for admitting the heavier fuel, for instance crude petroleum. This fuel is then at first preheated so that it gets an increased viscosity and will more easily fiow through the. carburettor, and the pre-heating takes place on account of the hot cooling Water which passes through the jacket surrounding the carburettor. At the upward stroke of the cylinder 7 the fuel, together with a sutlicient quantity of combustion air, in a more or less finely divided state is sucked through the non-return valve 21 into the chamber 19, which is surrounded by the hot exhaust gases and heated by the same, and then into the chamber 13, whereby the heating of the mixture and a partial atomization of the fuel particles take place. During the compression stroke following next the mixture is pro-compressed within the heated chamber 19 and by means of the heat therefrom and by the compression the temperature of the charge is raised sufficiently for ensuring a very good atomization of the fuel oil. This good atomization besides the fact that the mixture is exposed to the heat within the atomization chamber during a comparatively long period of time and to the precompression within said chamber, is further assisted by the circumstance that the mixture by the alternating suction and precompression in the atomization chamber is given an eddying motion to and fro the tube 22 and the space surrounding said tube. By this eddying motion of the mixture, which assists in the atomization of the fuel oil, the mixture is also brought intimately in contact with all the outer parts ofthe cylinder bottom 7 thereby assisting in effectively cooling the same. By influence from the water jackets surrounding the chamber 13 and at hand in the member 24 the said chamber and the channel 23 are always kept at a uniform and comparatively high temperature which fact is of influence for the smooth running of the engine, since the fuel mixture during its way to the cylinder 7 is not exposed to any great local cooling which otherwise might cause re-con densation of the fuel oil. The cooling jackets 28 extending below the cylinder bottom 11 assist in effectively preventing the transmission of heat down to the crank shaft housing containing the lubricant. With regard to the lubrication, as stated above, at each revolution a very small quantity of oil, perhaps a drop new and then or part of a drop, by means of the piston rod is brought into the chamber 13, and in said chamber the lubricant is blown away from the piston rod by means of the highly eddying fuel mixture. This has been observed to be of a substantial value for the perfect running of the engine. It is obvious that, when arriving at the complete atomization of the fuel oil as described above, the lubrication of the engine by means of the fuel oil or a lubricant added to the same by necessity must be unreliable. It is a known fact that small an amount of'lubricant as possible is to be used for the lubrication of the cylinder in combustion engines, and this object is arrived at in an unparalleled manner by the present invention, at least as far as two stroke cycle engines are concerned. The very minute quantity of lubricant oil auto matically introducedinto the chamber 13 by means of the piston rod 5 has been found to effect an ideal lubrication of the sliding surfaces of the cylinders 6 and 7 and every other means for lubrication or addition of lubricants to the fuel oil is not by far so good.

What I claim and Letters Patent is 1. In an engine of the two-cycle rear compression cylinder type, a compression cylinder intermediate the combustion chamber and crank-case, and a working piston the lower side of which acts as the compression piston in said compression cylinder, a jacketed casing forming a mixing chamber, a carburettor connected thereto, said mixing chamber being in constant inter-communication with said compression chamber whereby the mixture within said casing is alternately rarefied and densified for drawing upon the carburettor and effecting intimate mixture of the fuel thus educted from the carburettor, and means for passing the heated exhaust products of said engine through the jacket of said casing.

2. In an engine of the two-cycle rear compression cylinder type, a. combustion cylinder having a reentrant head, a compression cylinder intermediate the combustion cylinder and the crank, a working piston in said cylinders, having a cylindrical flange defining with its upper face and with said reentrant head a combustion chamber, said flange being ported and constituting a valve for controlling intake and exhaust ports in said combustion cylinder adjacent said redesire to secure by entrant head, the lower face of said piston acting as a compression piston in said compression cylinder, the latter being in commu nication wlth the intake port of said combustion cylinder, a jacketed casing forming a mixing chamber, a carburettor connected thereto, said mixing chamber being in con stant intercommunication with said compression chamber, whereby the mixture within said casing is alternately rarefied and densificd for drawing upon the carburettor, and effecting intimate mixture of the fuel thus educted from the carburettor, and means for passing the heated exhaust prod nets of said combustion cylinder through the jacket of said casing.

In testimony whereof I have signed my name to this specification.

ARTHUR OSKAR LEONARD WENNERBY. 

